The invention relates to a filter bag for vacuum cleaners, comprising a substantially plate-like connection member, which comprises a stationary base body with two superposed, aligned passage openings, more particularly manufactured of a board- or card-like material, and a sliding door, which is arranged between two base body layers and has a through opening, such door being more particularly made of film-like flexible material, the said sliding door extending outwards laterally between the base body layers and being able to be shifted from an open position, in which its through opening is in alignment with the passage openings, into a closed position closing the passage openings.
Both in the case of household vacuum cleaners and also of larger models able to be employed in industry filter bags--the term bag also including large filter sacks or the like--are used to receive the dust collected. In such equipment a suction current is produced by means of a vacuum cleaner blower which sweeps the dust into a suction duct, suction hose or the like and thence into the respective filter bag. The suspended dust in the drawn-in air is retained by the filter bag wall, whereas the air current free of dust passes through the filter bag wall and is then let off into the surroundings. Once the filter bag is full, it is removed and can be disposed of.
The fastening of the filter bag on the vacuum cleaner appliance is performed by means of the connection member attached to the filter bag adjacent to its inlet opening, such member being so arranged that the passage openings in the base body layers are in alignment with the inlet opening of the filter bag and all such openings together constitute an intake opening through which the dust laden air is introduced. With the aid of the sliding door it is possible for this intake opening or, respectively, the passage openings of the connection member to be shut, when the filter bag is moved from the vacuum cleaner appliance. It is in this manner that dust-is prevented from escaping from the discarded filter bag into the surroundings.
The German patent publication 2,407,478 A discloses a filter bag of the type initially mentioned, in the case of which the sliding door constituted by a paper strip has a folded end part bonded to the layers of the base body so that on tugging the projecting opposite end the folds are pulled out and the previously folded part takes up a position over the passage opening and closes the same.
Since the sliding door must be relatively long owing to its folds, this arrangement needs a relatively large quantity of material. In this respect it is to be taken into account that a relatively expensive special-purpose paper with a high tear strength has to be employed.
Furthermore the adhesive bonding of the end of the sliding door to one of the base body layers also involves the need not only for an additional manufacturing step but also the danger that the bond will not be able to withstand the force acting on the sliding door when closing the filter bag so that the sliding door may be completely withdrawn and the intake opening would be re-opened.